Sterilisation is a mandatory process for almost all industries. The rate of growth of the microorganism is very fast, they simply multiply. If not sterilised on time, they can contaminate the environment and start impacting the people in the surroundings. To curb this, different sterilisation techniques are used and some of them are;
• Hot air sterilisation
• Streaming steam
• Chemical sterilisation
This article will shed some spotlight on above-mentioned techniques. However, most of them are popular in the medical industry.
There are some objects which are sterilised by directly exposing to flame. The temperature of the flame is more than enough to kill the bacteria or microorganism instantly that are present on the surface of the object. However, this process is bit risky and should be avoided if there are other methods possible. There is a possibility that spattering happens due to the presence of microorganism present in the droplets. So always dry the objects before beginning the process.
Hot air sterilisation is now gaining too much of popularity due to ease of implementation. There are no hazards associated with this process. Moreover, it is suitable for every type of object be it glass or metal. This is highly preferred in medical laboratories for sterilising borosilicate glassware. First of all, the objects are washed thoroughly with the water and then placed in the hot air oven at 160°C for approximately 2 hours. This treatment sterilises the objects completely. As this temperature completely disrupt the oxygen supply of spores.
This machine is very similar to an oven, except there is a placement of fan in the chamber. This air is responsible for uniform distribution of the heat throughout the chamber. The inner body or the chamber is made up of stainless steel to eliminate all chances of corrosion. Whereas, the outer body is made up of mild steel. Due to the difference in body, there is a large difference in the temperature of the outer body and is completely safe to touch when it is in operating mode.
The principle of streaming steam is to expose the material to be sterilised directly to the live stream. Also called Arnold steam steriliser, in this practice, the material is sterilised at 212°F. It consists of a double bottom pan which is filled partially with water. The water is heated up to boiling point over a flame. As soon as it reaches the boiling point, it is replaced through an opening in the pan rapidly as it evaporates. The steam moves towards the opening and evacuates through the opening in the top and around the door. Usually, the exposure of 90 minutes is sufficient for effective sterilisation.
Autoclaving is the process of exposing the materials to be sterilised in moist pressure. It is a laboratory equipment used in medical laboratories and other laboratories. However, there are different types of autoclaves but they all work on the common principle of pressure steaming. It is a cavity style machine having a cylinder where steam forms. With the increase in heating time, the pressure inside the cylinder increases. The pressure inside the cylinder is approximately 15lb/inch2. The best part about using an autoclave is that the sterilisation process is not very long. It takes about 15 minutes to effectively sterilise the instruments, which otherwise takes 2 hours in hot air oven.
In some industries, sterilisation is done at quite a lot temperature. Using refrigeration techniques, the pure cultures are preserved at a temperature range of 0-4°C. This process is continued for a time span of 2-3 weeks for bacteria and 3-4 months for fungi. This rapidly decreases the growth of the microorganisms. However, the nutrients are slowly utilised but their growth is not inhibited completely. The waste products are released into the medium. This eventually leads to the death of microorganisms.
Chemical Methods of Sterilization
In certain industries, use of nonvolatile chemicals is incorporated to treat glassware and other objects like desks, gloves, masks etc. The main aim of using these chemicals is to diminish the growth of microorganisms that could be potentially dangerous. Apart from killing the bacteria, these treatment stops the growth of other spores and microorganisms in the surroundings.